Silicon Carbide Micropowder (Overflow / Siphon / Air-Classified)

Overview

SiC micropowder is the sub-micron-to-tens-of-microns particle fraction of silicon carbide — the form that serves coatings, ceramic forming, precision polishing, and high-tech filter applications. Production runs two complementary process routes that the silicon-carbide industry treats as related but distinct families:

Overflow / Siphon (wet-sedimentation) micropowder — JIS240 to JIS10000 (D50 57 → 0.5 μm) per JIS R6001-1998. The crushed SiC enters a water-sedimentation tank; the suspension is graded by adjusting overflow water velocity (small particles overflow, large particles settle) or siphon position (medium-cut particles siphoned, finest particles stay in suspension). Tightly controlled D3 / D50 / D94 cuts, slightly rounded particle shape from the wet-cycle, water-quench-treated surfaces.

FEPA Air-Classified (dry-centrifugal) micropowder — F230 to F2000 (D50 53 → 0.5 μm) per FEPA 42-GB-1984 / ISO 8486-2 / GB/T 2481.2. The crushed and milled SiC is fed through a centrifugal air classifier; coarse particles drop out, fines exit with the air stream. Sharper-edged particle shape from the dry route, narrower size distribution at sub-micron cuts.

Both routes give SiC purity ≥99.0% (#240 to #3000) and ≥98.5% (#4000 to #10000), with specific gravity ≥3.16, Fe₂O₃ ≤0.20%, free-C ≤0.20%. RoHS / REACH / SVHC clean — fit for food-contact (non-stick cookware) and medical-adjacent (ceramic-membrane food/dairy filter) applications.

Technical Specifications

Applications

Non-Stick Cookware Ceramic Coating

1–5 μm SiC micropowder (typically JIS1500 or F1000) added to the ceramic top-coat at 5–15 wt%. Provides wear protection (knife and metal-utensil scratch resistance), thermal shock resistance to 200°C cooking-fire transients, and a hard ceramic barrier between the PTFE / silicone top-layer and the substrate. RoHS / REACH compliance is mandatory for cookware suppliers (EU food-contact regulations); SiC at ≥99% purity satisfies all current food-contact restrictions. The Chinese cookware industry consumes ~5000 t/yr of this grade.

Diesel Particulate Filter (DPF) Substrate

Extruded honeycomb wall-flow ceramic from sintering-grade SiC micropowder (typically 5–10 μm with controlled distribution and 0.1–0.5% B / Y₂O₃ sintering aid). Fired in argon at 2200°C to a fully dense honeycomb. Capture efficiency ≥99.6% by gravimetric measurement on a Euro VI / China VI diesel engine. Cordierite competes on cost but SiC has 30% higher thermal-shock resistance — hence dominance in commercial diesel and high-output marine engines.

Ceramic Brake Pads (High-Speed Rail, EV, Premium Passenger Car)

SiC micropowder (5–25 μm typical) as reinforcement filler in carbon-ceramic brake discs and brake pads. Brake disc life is 30 % longer than cast iron at half the weight; thermal stability eliminates brake fade above 600°C. EV regenerative-braking systems consume the largest share.

Foamed Ceramic Filter for Molten Metal Casting

Sintering-grade SiC micropowder is slurry-impregnated into a polyurethane reticulate sponge, then pyrolysed and sintered to give an open-cell SiC foam at 10–60 ppi cell density. Filters molten aluminium, copper, and steel in foundries; removes oxide inclusions before pouring.

Ceramic Membrane Micro / Ultrafiltration

Tubular and flat-sheet SiC membrane assembled from successive layers of decreasing SiC particle size — coarse macroporous support to selective microporous top layer. Serves food and dairy separation (milk fat fractionation, beer clarification), pharmaceutical sterile filtration, oilfield produced-water deoiling, and hot-gas filtration at 600–1000°C where polymer membranes fail.

Sapphire and Optical Polishing Slurry

Lapping and polishing slurry for sapphire LED substrate (final-stage finish), optical-glass lenses, and semiconductor wafer-level polishing. SiC micropowder F1500–F2000 in glycol or oil carrier. Polish rate 0.5–2 μm/min; final-surface roughness Ra below 50 nm.

Coated Abrasive Fine-Grit Polishing Paper

P800–P3000 fine-grit polishing paper for automotive body refinishing, wood lacquer polishing, and metal final-finish work. Sourced from FEPA air-classified micropowder.

Precision-Ceramic Raw Material

Silicone-rubber filler (high-temperature electrical insulation), electronic substrate body (high-frequency low-loss), and reaction-bonded SiC (RBSC) precursor coarse fraction (F240). See the Sintered Silicon Carbide page for full RBSC / SSiC / R-SiC powder details.

Selection Guide vs Sand and Sintering Grades

Choose SiC micropowder for: any application requiring particle median below 60 μm; coating / cookware / DPF / brake / membrane / polishing / fine ceramic. Within the family, choose FEPA air-classified for narrow distribution at sub-micron cuts; choose JIS overflow/siphon for wet-cycle-treated particles in slurry applications.

For applications above 60 μm particle median, use SiC abrasive sand (F14–F220) — see the Black or Green SiC pages.

For ceramic-body / structural-ceramic applications requiring sintering to dense bodies, use sintering-grade powders (RBSC F240+F1200, SSiC W63–W0.5, R-SiC RS07/RS100) — see the Sintered Silicon Carbide page.

Equivalent Grades

• Saint-Gobain Sika Micronized GC — European premium micropowder
• Washington Mills Micro-Grit Series — North American precision micropowder
• Showa Denko GC# Micropowder — Japanese optical/cookware-grade
• Performance Materials Microgrit — premium polishing grades
• Generic Chinese SiC micropowder — commodity grade ≥99%, JIS or FEPA standard